/*
 * Copyright (c) 2007-2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: FilterExprIteratorSimple.java,v 1.2.4.2 2005/09/14 19:45:21 jeffsuttor Exp $
 */
package com.sun.org.apache.xpath.internal.axes;

import com.sun.org.apache.xml.internal.dtm.Axis;
import com.sun.org.apache.xml.internal.dtm.DTM;
import com.sun.org.apache.xml.internal.utils.PrefixResolver;
import com.sun.org.apache.xpath.internal.Expression;
import com.sun.org.apache.xpath.internal.ExpressionOwner;
import com.sun.org.apache.xpath.internal.VariableStack;
import com.sun.org.apache.xpath.internal.XPathContext;
import com.sun.org.apache.xpath.internal.XPathVisitor;
import com.sun.org.apache.xpath.internal.objects.XNodeSet;

/**
 * Class to use for one-step iteration that doesn't have a predicate, and
 * doesn't need to set the context.
 */
public class FilterExprIteratorSimple extends LocPathIterator {
    static final long serialVersionUID = -6978977187025375579L;
    /** The contained expression. Should be non-null.
     *  @serial   */
    private Expression m_expr;

    /** The result of executing m_expr.  Needs to be deep cloned on clone op.  */
    transient private XNodeSet m_exprObj;

    private boolean m_mustHardReset = false;
    private boolean m_canDetachNodeset = true;

    /**
     * Create a FilterExprIteratorSimple object.
     *
     */
    public FilterExprIteratorSimple() {
        super(null);
    }

    /**
     * Create a FilterExprIteratorSimple object.
     *
     */
    public FilterExprIteratorSimple(Expression expr) {
        super(null);
        m_expr = expr;
    }

    /**
     * Initialize the context values for this expression
     * after it is cloned.
     *
     * @param context The XPath runtime context for this
     * transformation.
     */
    public void setRoot(int context, Object environment) {
        super.setRoot(context, environment);
        m_exprObj = executeFilterExpr(context, m_execContext, getPrefixResolver(), getIsTopLevel(), m_stackFrame, m_expr);
    }

    /**
     * Execute the expression.  Meant for reuse by other FilterExpr iterators
     * that are not derived from this object.
     */
    public static XNodeSet executeFilterExpr(int context, XPathContext xctxt, PrefixResolver prefixResolver, boolean isTopLevel, int stackFrame, Expression expr) throws com.sun.org.apache.xml.internal.utils.WrappedRuntimeException {
        PrefixResolver savedResolver = xctxt.getNamespaceContext();
        XNodeSet result = null;

        try {
            xctxt.pushCurrentNode(context);
            xctxt.setNamespaceContext(prefixResolver);

            // The setRoot operation can take place with a reset operation,
            // and so we may not be in the context of LocPathIterator#nextNode,
            // so we have to set up the variable context, execute the expression,
            // and then restore the variable context.

            if (isTopLevel) {
                // System.out.println("calling m_expr.execute(getXPathContext())");
                VariableStack vars = xctxt.getVarStack();

                // These three statements need to be combined into one operation.
                int savedStart = vars.getStackFrame();
                vars.setStackFrame(stackFrame);

                result = (com.sun.org.apache.xpath.internal.objects.XNodeSet) expr.execute(xctxt);
                result.setShouldCacheNodes(true);

                // These two statements need to be combined into one operation.
                vars.setStackFrame(savedStart);
            } else
                result = (com.sun.org.apache.xpath.internal.objects.XNodeSet) expr.execute(xctxt);

        } catch (javax.xml.transform.TransformerException se) {

            // TODO: Fix...
            throw new com.sun.org.apache.xml.internal.utils.WrappedRuntimeException(se);
        } finally {
            xctxt.popCurrentNode();
            xctxt.setNamespaceContext(savedResolver);
        }
        return result;
    }

    /**
     *  Returns the next node in the set and advances the position of the
     * iterator in the set. After a NodeIterator is created, the first call
     * to nextNode() returns the first node in the set.
     *
     * @return  The next <code>Node</code> in the set being iterated over, or
     *   <code>null</code> if there are no more members in that set.
     */
    public int nextNode() {
        if (m_foundLast)
            return DTM.NULL;

        int next;

        if (null != m_exprObj) {
            m_lastFetched = next = m_exprObj.nextNode();
        } else
            m_lastFetched = next = DTM.NULL;

        // m_lastFetched = next;
        if (DTM.NULL != next) {
            m_pos++;
            return next;
        } else {
            m_foundLast = true;

            return DTM.NULL;
        }
    }

    /**
     * Detaches the walker from the set which it iterated over, releasing
     * any computational resources and placing the iterator in the INVALID
     * state.
     */
    public void detach() {
        if (m_allowDetach) {
            super.detach();
            m_exprObj.detach();
            m_exprObj = null;
        }
    }

    /**
     * This function is used to fixup variables from QNames to stack frame
     * indexes at stylesheet build time.
     * @param vars List of QNames that correspond to variables.  This list
     * should be searched backwards for the first qualified name that
     * corresponds to the variable reference qname.  The position of the
     * QName in the vector from the start of the vector will be its position
     * in the stack frame (but variables above the globalsTop value will need
     * to be offset to the current stack frame).
     */
    public void fixupVariables(java.util.Vector vars, int globalsSize) {
        super.fixupVariables(vars, globalsSize);
        m_expr.fixupVariables(vars, globalsSize);
    }

    /**
     * Get the inner contained expression of this filter.
     */
    public Expression getInnerExpression() {
        return m_expr;
    }

    /**
     * Set the inner contained expression of this filter.
     */
    public void setInnerExpression(Expression expr) {
        expr.exprSetParent(this);
        m_expr = expr;
    }

    /**
     * Get the analysis bits for this walker, as defined in the WalkerFactory.
     * @return One of WalkerFactory#BIT_DESCENDANT, etc.
     */
    public int getAnalysisBits() {
        if (null != m_expr && m_expr instanceof PathComponent) {
            return ((PathComponent) m_expr).getAnalysisBits();
        }
        return WalkerFactory.BIT_FILTER;
    }

    /**
     * Returns true if all the nodes in the iteration well be returned in document
     * order.
     * Warning: This can only be called after setRoot has been called!
     *
     * @return true as a default.
     */
    public boolean isDocOrdered() {
        return m_exprObj.isDocOrdered();
    }

    class filterExprOwner implements ExpressionOwner {
        /**
        * @see ExpressionOwner#getExpression()
        */
        public Expression getExpression() {
            return m_expr;
        }

        /**
         * @see ExpressionOwner#setExpression(Expression)
         */
        public void setExpression(Expression exp) {
            exp.exprSetParent(FilterExprIteratorSimple.this);
            m_expr = exp;
        }

    }

    /**
     * This will traverse the heararchy, calling the visitor for
     * each member.  If the called visitor method returns
     * false, the subtree should not be called.
     *
     * @param visitor The visitor whose appropriate method will be called.
     */
    public void callPredicateVisitors(XPathVisitor visitor) {
        m_expr.callVisitors(new filterExprOwner(), visitor);

        super.callPredicateVisitors(visitor);
    }

    /**
     * @see Expression#deepEquals(Expression)
     */
    public boolean deepEquals(Expression expr) {
        if (!super.deepEquals(expr))
            return false;

        FilterExprIteratorSimple fet = (FilterExprIteratorSimple) expr;
        if (!m_expr.deepEquals(fet.m_expr))
            return false;

        return true;
    }

    /**
     * Returns the axis being iterated, if it is known.
     *
     * @return Axis.CHILD, etc., or -1 if the axis is not known or is of multiple
     * types.
     */
    public int getAxis() {
        if (null != m_exprObj)
            return m_exprObj.getAxis();
        else
            return Axis.FILTEREDLIST;
    }

}
